about Connection Interval

RE: about Connection Interval

Hung Bui — Fri, 11 Oct 2024 12:50:43 GMT

Hi Tomokuni,

Unfortunately the sniffer traces you captured don't provide much useful information because it didn't follow the connection.
We have a tutorial that you can follow here regarding the sniffer: https://academy.nordicsemi.com/courses/bluetooth-low-energy-fundamentals/lessons/lesson-6-bluetooth-le-sniffer/

BLE_ACL_CONN_INTERVAL is the normal connection interval, yes.

You can reduce the time from starting advertising until connection established by advertising with shorter advertising interval.

RE: about Connection Interval

tommy — Fri, 11 Oct 2024 10:46:13 GMT

"Link time" means the elapsed time to establish the connection between Central and Peripheral.
Here are the log of connection captured by the sniffer.
We have changed the value of BLE_ACL_CONN_INTERVA, and tried 30msec and 100msec.

(BTW,BLE_ACL_CONN_INTERVA surely define the Connection interval as circled in red?)

30ms_CONNECTION_FAIL-SUCCESS.pcapng
-> once failed, but SUCCESSED afterward

30ms_CONNECTION_SUCCESS.pcapng
-> connection successed

100ms_CONNECTION_FAIL.pcapng

-> connection failed

100ms_CONNECTION_SUCCESS.pcapng

-> connection successed

In our environment, we have found the following result;

30msec: the elapsed time surely reduced, however sometimes it becomes easier for the connection to be lost and recovered.

100msec:the connection lost rarely happened.

Is there some way to optimize this parameter?
or are there any optimized value for each SDK?

devzone.nordicsemi.com/.../2677.log.zip

RE: about Connection Interval

Hung Bui — Thu, 26 Sep 2024 12:36:24 GMT

Hi Tomokuni,
Please provide more information about the issue: Unable to pair two devices / Sometimes fails to link with one device

When you reduce the connection interval, the data exchange can be faster and result in shorter time for service discovery and pairing.
Please elaborate what you meant by "link time"

My suggestion is to use the sniffer to capture the connection and pairing.